Estimation of solubility of solids in supercritical carbon dioxide

Peng-Robinson equation of state (PR EOS) was chosen for modeling the thermodynamic behavior of supercritical (SC) - CO₂/Solid systems. The necessary critical constants and acentric factor of the solute were obtained by the Sigmund and Trebble(1992)method based on the molecular weight and boiling temperature, and the vapor pressure of the solute was calculated by its melting temperature and heat of fusion. This approach compared very favorably with the conventional corresponding state theory, but without using critical constants and vapor pressure of solutes. Four mixing rules were tested for the calculation of solid solubility in SC - CO_2̇ van der Waals(vdW) mixing rule with one parameter was considered to be most suitable for the estimation of solubility. A simple correlation was developed for the SC - CO₂/solid binary interaction coefficient k_ij with the melting temperature of pure solutes. The solubilities of solids in SC-CO₂ were estimated for eleven binary systems at various temperatures, the total absolute average relative deviation (AARD)was 25.0%.